This invention relates hinged vehicle safety devices and more particularly to actuators for hinged vehicle safety devices.
U.S. Pat. No. 5,357,239 granted to Ronald C. Lamparter Oct. 18, 1994 discloses an actuating device for operating a safety unit, such as a crossing arm or a stop sign, that moves between a retracted position adjacent the vehicle and an extended position extending outwardly from the vehicle. A housing is mounted on the vehicle and a bracket is pivotally mounted on the housing for movement about a vertical pivot axis between a retracted position and an extended position. The actuating device includes a drive mechanism having a drive unit for pivoting the bracket about the pivot axis and an electric motor for driving the drive unit.
U.S. Pat. No. 5,719,553 granted to Ronald C. Lamparter Feb. 17, 1998 discloses a sealed actuator assembly for hinged vehicle safety devices, such as a crossing arm or a stop sign. The sealed actuator assembly is attached to the vehicle and includes the electrical and mechanical components that pivot the hinged safety device from a stored position adjacent the bus to an operative position extending outwardly of the bus. These components and wiring harnesses are protected in an outer sealed housing that has a removable cover to facilitate installation and repair. Installation and repair is further enhanced by a removable inner housing sub-assembly that carries a motor control circuit for the electric motor and provides additional protection for the electric motor.
The actuators described above are very satisfactory for their intended purpose. However, both actuators use an electric motor to pivot the vehicle safety device, which is fine because all vehicles include an electric storage battery for a power source. On the other hand, some vehicles and school busses in particular, normally include a fluid power source such as an air pump for operating other systems and accessories. The fluid power source may be preferred over the electrical power source for one reason or another. However, the fluid power source cannot operate the actuators described above.
This invention provides an actuator assembly for hinged vehicle safety devices, such as a stop sign or a crossing arm, that is fluid operated, preferably by pressurized air. The actuator assembly has a housing with a cylinder attached inside the housing. A piston slides in the cylinder and forms a fluid chamber between the piston and a closed end of the cylinder. A passage extends into the housing and opens into the fluid chamber. A lever arm is pivotally supported at one end inside the housing for pivotal movement between retracted and extended positions, the lever arm extending over the cylinder and having a lip at an opposite end that is spaced from the cylinder. A pivot arm engages an upper surface of the piston at one end and the lever arm at an opposite end to transfer motion from the piston to the lever arm. A rotor is rotationally mounted in the housing for movement between retracted and extended positions, the rotor having a spool at one end and an eccentric arm next to the spool that engages the lip of the lever arm. A torsion spring encircles the spool with one end engaging the rotor and an opposite end engaging a stop in the housing so that the eccentric arm is biased against the lip of the lever arm and the rotor and the lever arm are biased to their respective retracted positions. When pressurized air is admitted to the chamber, the piston extends and pivots the lever arm toward the extended position. The lever arm in turn rotates the rotor and the safety device attached to it toward the extended position.
The rotor preferably has a spool and a torsion spring at each end for balanced operation. In another preferred form, the piston has a deep cavity in an upper surface that includes a concentric ball socket, and the pivot arm has a ball at the one end that engages the ball socket to minimize height requirements. The housing preferably has a base and a removable cover while several internal parts preferably form a sub-assembly to make assembly easier. To this same end, the actuator preferably includes a lever arm pivot attachment that is an integral part of the base member of the subassembly and that is designed to permit snap assembly of the lever arm to the lever arm pivot attachment.